1. Field of the Invention
The present invention relates to a vehicle lighting device which forms a high beam light distribution pattern by directing light emitted from a light source unit to travel forward, and more particularly to a technique which increases the visibility without dazzling the drivers of a preceding vehicle and an oncoming vehicle.
2. Description of the Background Art
A projector type lamp unit provided in a headlight which is an automotive lamp typically includes a light source for emitting light, a reflector for reflecting the light from the light source, a projection lens for projecting forward the light reflected by the reflector, a holder which fixes the projection lens in place relative to the reflector, and a shade for interrupting the passage of part of the light traveling from the reflector to the projection lens. During driving at night, the headlight is preferably set to a high beam when there is no vehicle being driven ahead of the subject vehicle and to a low beam when there is a vehicle being driven ahead thereof depending on a distance to the preceding or oncoming vehicle in order not only to improve the visibility of the driver of the subject vehicle but also to give no glare to the driver of the preceding or oncoming vehicle.
Among projector type headlamps, there are headlamps which can emit both a high beam and a low beam. In a projector type headlamp of this type, a shade is supported on a holder via rotational pins, whereby the shade is allowed to rotate around a horizontal axis which connects both the rotational pins between a low beam forming position and a high beam forming position.
When situated in the low beam forming position, the shade interrupts the passage of part of the reflected light from the reflector so as to remove an upwardly directed light emitted from the lamp unit to thereby obtain a low beam forming light which is projected downwardly. In one example, a low beam light distribution pattern is formed which has a Z-type cut-off line which is staggered in a horizontal direction.
When situated in the high beam forming position, the shade cancels the interruption of the passage of the reflected light from the reflector so as to permit the emission of the upwardly directed light from the lamp unit, whereby the light is allowed to be emitted toward an area above the cut-off line to form a high beam light distribution pattern which improves the visibility in a far field area.
In a conventional automotive lamp, only a single high beam light distribution pattern was obtained by a high beam forming light. Consequently, an elaborate formation of suitable illumination areas for various vehicle driving conditions is difficult. Namely, in the event that there are no pedestrians and no preceding and oncoming vehicles ahead of the subject vehicle, by forming the conventional high beam light distribution pattern, a good visibility in a far field area is secured, while no other parties are dazzled. However, in the event that there are pedestrians and oncoming vehicles, there have been cases where the pedestrians and oncoming vehicles are somewhat dazzled depending on an environment where the subject vehicle is being driven. In addition, in the event that there is a preceding vehicle ahead of the subject vehicle, although the high beam is not normally switched on, the driver of the subject vehicle wishes to be able to see pedestrians on a side of a road. In such a case, in the event that the high beam is turned on, the driver of the preceding vehicle is dazzled.
The invention was made in view of these situations, and an object thereof is to provide a vehicle lighting device which can set an optimum high beam illumination area according to the presence of a pedestrian and a preceding vehicle or an oncoming vehicle which is being driven right ahead of the subject vehicle, so as to realize an increase in the visibility of the pedestrian and a reduction in the possibility of dazzling the pedestrian, preceding vehicle, and oncoming vehicle.